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Track: Water Resources
Kristine L. Verdin
Hughes STX Corporation/USGS EROS Data Center
Mundt Federal Building
Sioux Falls, SD 57198
Telephone: 605-594-6002
Fax: 605-594-6529
E-mail: kverdin@edcsgw6.cr.usgs.gov
A System for Topologically Coding Global Drainage Basins and Stream Networks
Development of a global digital elevation model at 30 arc/second resolution (approximately 1 kilometer) at the EROS Data Center, known as GTOPO30, has made it possible to obtain derivative products for hydrologic studies. Tools in ARCGRID were used to automatically extract river basins and drainage networks, which were subsequently vectorized and tagged with attributes according to the numbering scheme developed by Otto Pfafstetter, a Brazilian engineer. The Pfafstetter system is based upon the topology of the drainage network and the size of the surface areas drained. Its numbering scheme is selfreplicating, making it possible to provide identification numbers to the level of the smallest subbasins extractable from a DEM. The system's appeal stems from its economy of digits, the topological information the digits carry, and its global applicability. Avenue scripts were written to provide an interface to the basins and drainage networks with ArcView. Queries that exploit the topological information in
the Pfafstetter digits are programmed in the scripts. Examples are, for a given location, the automatic identification of all upstream subbasins, all upstream river reaches, or all downstream reaches. The result is a global system of unique identification numbers for all topographic drainage features and a convenient interface to manipulate them.
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